Best way to use create a slide on hover?

Best way to use create a slide on hover?

I'm looking to slide a div, as in change it's left-margin (using positive and negative values), whenever someone hovers over another element. This element happens to be an image of an arrow, but that doesn't matter. What is the best way to do this exactly? I want it to to a smooth slide and continue to slide as long as the user is in that hover state....